The present invention relates to a grinding machine, and more particularly to a grindstone shield and a worktable of the grinding machine. The grindstone shield is provided with a receiving portion for collecting the dust produced in the grinding process, and with a connecting tube that can be fastened to a vacuum cleaner, and further with an angle adjusting plate pivoted to the grindstone shield for supporting a work piece and for adjusting the inclination of the worktable of the grinding machine. The angle adjusting plate is provided with a plurality of concave retaining surfaces which are situated respectively at the predetermined angles and are intended for retaining therein the locating element disposed on the grindstone shield, so as to facilitate the job of adjusting the inclination of the worktable and locating the work piece on the worktable.
The prior art grinding machine is generally provided horizontally at the center thereof with a motor having two end portions, each of which is coupled with a grindstone so that the motor drives the grindstones synchronously. In addition, each grindstone has a shield disposed thereover. A worktable for supporting the work piece is mounted in front of the shield. Such prior art grinding machine is in itself defective in that the dust produced in the grinding process is a potential health hazard to a grinder, in view of the fact that the centrifugal force of the rotating grindstone and the turbulent air flow generated by the rotating grindstone make it difficult to contain the dust so produced.
The worktable of the prior art grinding machine is provided with an angle measuring plate having a size corresponding to one quarter of a disk. Such angle measuring plate is fastened to the outer side of the shield of the grindstone by means of a bolt and is provided with a shaft pivoted to the shield. As a result, a grinder is able to adjust the bevel between the worktable and the grindstone by using the shaft as a central of axis and by using the distance between the shaft and the bolt as a radius. Thereafter, the worktable is locked in that position by tightening the bolt. The desired angle so adjusted between the worktable and the grindstone is indicated on the bevel scale of the angle measuring plate by a pointer that is fastened to the bolt.
The prior art method of adjusting the bevel between the worktable and the grindstone is rather cumbersome and inefficient. For example, the most commonly used grinding angles are zero degree, 15 degrees, 30 degrees, 45 degrees, etc., which must be individually adjusted and checked each time when the use of such bevel is called for.